Method of manufacturing granulated potassium fertilizers from potassium sulphate or from sulphate of potassium and magnesium



Patented Feb. s, 1938 UNITED STATES PATENT OFFICE METHOD OF ,MANUFACTURING GRANU- LATED POTASSIUM FERTILIZERS FROM POTASSIUM SULPHATE OR FROM SUL- PHA'IE OF POTASSIUM AND MAGNESIUM Karl Haase and Helmut Werth, Bleicherode, Germany, assignors to the firm Preusaische Bergwerksund fliitten-Aktiengeaellachaft, Berlin,

Germany No Drawing.

Application January 18, 1935, Se-

rial No. 2,055. in Germany September 15,

:1 Claims. (01. 71-01) ature of from 25 to 40 C. The technical potassium sulphate obtained in this way contains always a few percents of M8304 as contamination. The products are floury, in consequence 1 whereofthey dust when being used as fertilizing agents after the drying, and besides, they are insuillciently strewable and likewise insuillciently handable.

Now, the above-mentioned fertilizing salts can,

1 according to the present invention, be converted into more or less coarsely granulated, hard and well-shaped agglomerates by mixing the starting material with dry burnt lime, or calcium oxide respectively, and adding then water to this mix- 20 ture; or by employing said lime or calcium oxide in the form of an aqueous suspension, the amount of the lime or oxidebeing in both cases small in proportion .to the amount of the starting material, whereafter the moist-crumbly product 5 obtained is transformed into granules which are dried until they have become hard. The drying and the hardening phase may be carried out in any of the known and heated drying drums used in the potassium industry.

30 By the interaction of the burnt or slaked lime (CaO) with equivalent parts of magnesium sulphate of the technical potassium sulphate, or of the potassium sulphate-magnesium sulphate respectively, and owing to the formation of cal- 35 clum sulphate and magnesium-hydroxide by said interaction the individual salt particles are cemented together so as to constitute an agglomerate.

In order to obtain a suilicient granulation,

40 preferably from 4 to 5% of the burnt lime (containing about 80% of CaO) relatively to the amount of salt to be formed are used, and so much water is added that the moist agglomerate contains about from to of H20.

45 It is known, to produce the agglomeration of salts by mixing them with substances exerting a cementing action, or by adding substances forming a compound able to exert such an action by a chemical conversion with .a portion of the 50 starting material, but in all'those processes other startingmaterials (mixed fertilizers, phosphorus fertilizenpotasslum chloride fertilizer) or (and) other additional substances are used. -It could,

not be. foreseen that potassium sulphate and is potassium sulphate-magnesium sulphate could phate with solid potassium chloride at a temper-,

be agglomerated with the low-priced and everywhere obtainable burnt lime 'in the abovedescribed simple and economical manner.

Example 1 v 5 96 kg. of commercial potassium sulphate are intimately mixed with 4 kg. of finely ground burnt lime having a CaO-content of about 80%, whereafter the mixture is uniformly soaked with 18 liters of water. The thereby obtained moistcrumblyagglomerate is then ,shaped and dried to hardness in a heated rotary drum.

Screen anal sis Screen analysis 1 Granulation shares of the start ng of the granulated material product Mm. diam. Percent 4 Permit Above 5 0, 0 8, 4 iggve $2. 0, 7 l2, 9 ve l 1 58, 6 Above 0,5- 01s as 20 Below 0,5 91, 7 ll, 3

, Example 2 96 kg. of commercial potassium sulphatemagnesium sulphate are uniformly mixed with a suspension of 4 kg, of burnt lime (having a content of CaO of about 80%) in 20,liters of water. The thereby obtained agglomerate is then shaped in a heated rotary drum and dried therein to hardness.

Screen analglsis Screen analysis Granulation shares of the start g of the granulated material product,

Percent Percent Weclaimzl. The method of manufacturing a granulated fertilizer from technical potassium sulphate containing magnesium salts selected from the group consisting of technical potassium sulphatemagnesium sulphate combinations, comprising adding thereto an amount small in proportion to the amount of the potassium'salt, of quick lime (CaO) and intimately mixing the aforesaid materials in the presence of a quantity of water amounting to from 15% to 20% of the moist mixture, and agitating the moist crumbly product in a heated rotary drum, drying the mixture 56 in a manner to granulate same into hard dry granules.

2. The method of manufacturing a granulated I fertilizer from technical potassium sulphate containing magnesium salts selected from the group consisting of technical potassium sulphatemagnesium sulphate combinations, comprisingadding thereto an amount small in proportion to the amount of the potassium salt, of dry pulverulent burnt lime (CaO) and intimately mixing the aforesaid materials, adding subsequently a sumcient quantity of water and likewise intimately mixing it with the aforesaid mixture, agitating the moist crumbly product containing from 15% to 20% of water, drying the mixture in a heated rotary drum in a manner to granulate same into hard dry granules. I

a. The method of manufacturing a granulated fertilizer from technical potassium sulphate containing magnesium salts selected from the group consisting .of technical potassium sulphatemagnesium sulphate combinations comprising adding thereto an amount small in proportion to. the amount'of the potassium salt, of an aqueous suspension of burnt lime (CaO) and intimately mixing the aforesaid materials in the presence or a quantity of water amounting to from 15% to- 20% of the moist mixture, agitating the moist crumbly product containing from 15% to 20% of water, drying the mixture in a heated rotary in a manner to granuiate th product intohard dry granules. Y

' KARL mass. rmmu'r waa'm; 

